One embodiment of an apparatus and method for treating agricultural animal wastewater that costs less to build, is easy to operate, and requires little energy input. The method employs natural systems for wastewater treatment; an initial anaerobic digestion treatment followed by batch floating aquatic plant treatment. The batch floating aquatic plant treatment of effluent and subsequent batch discharge provides increased control of the treatment process. Opportunistic collection and use of biogas and floating aquatic biomass results in additional benefits. The apparatus reduces the cost and land area required for the system by subdividing a lagoon into an anaerobic digestion treatment zone below the apparatus and a floating aquatic plant treatment zone above the apparatus. In addition, the apparatus is disposed in the lagoon in such a way that it facilitates the collection of biogas evolving from anaerobic digestion treatment beneath the apparatus by diverting it to areas to be collected.
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1. A method for treating wastewater, comprising:
(a) conveying said wastewater to a first zone, said first zone being of predetermined size and conducive to anaerobic digestion treatment,
(b) providing said first zone where:
(1) said wastewater is treated via anaerobic digestion,
(2) a once treated effluent is produced following anaerobic digestion, and
(3) bottom sludge is periodically removed,
(c) conveying said once treated effluent from said first zone to a second zone, said second zone being:
(1) of predetermined size,
(2) exposed to sunlight and the atmosphere, and
(3) conducive to floating aquatic plant treatment,
(d) conditioning said once treated effluent prior to floating aquatic plant treatment,
(e) providing said second zone where:
(1) batches of said once treated effluent receive floating aquatic plant treatment by growing a multitude of at least one type of floating aquatic plant on the surface of said once treated effluent,
(2) batches of a twice treated effluent are produced following floating aquatic plant treatment,
(3) floating aquatic plant biomass from floating aquatic plant growth is periodically harvested, and
(4) bottom sludge is periodically removed,
(f) discharging batches of said twice treated effluent from said second zone,
whereby said wastewater is treated by anaerobic digestion in said first zone and conditioning of said once treated effluent facilitates floating aquatic plant treatment in said second zone.
16. An apparatus for treatment of wastewater in a reservoir, comprising:
(a) a sheet of material, said sheet of material being flexible, impermeable, of predetermined size, and disposed in said reservoir such that:
(1) a first zone conducive to anaerobic digestion treatment is created below said sheet of material where:
(A) said wastewater is treated via anaerobic digestion,
(B) a once treated effluent is produced following anaerobic digestion, and
(C) bottom sludge is periodically removed,
(2) a second zone exposed to the sun and atmosphere and conducive to floating aquatic plant treatment is created above said sheet of material where:
(A) batches of said once treated effluent receives floating aquatic plant treatment by growing a multitude of at least one type of floating aquatic plant on the surface of said once treated effluent,
(B) batches of a twice treated effluent are produced following floating aquatic plant treatment,
(C) floating aquatic plant biomass from floating aquatic plant growth is periodically harvested, and
(D) bottom sludge is periodically removed,
(3) sufficient slack is provided in said sheet of material to compensate for changes in the liquid volume of at least one of said first zone and said second zone,
(b) a first means for conveying said wastewater to said first zone,
(c) a second means for conveying said once treated effluent from said first zone to said second zone, and
(d) a third means for discharging batches of said twice treated effluent from said second zone,
whereby said sheet of material is disposed in said reservoir such that said first zone conducive to anaerobic digestion treatment and said second zone conducive to floating aquatic plant treatment are created, and sufficient slack is provided in said sheet of material to compensate for changes in the liquid volume of at least one of said first zone and said second zone.
24. An apparatus for treatment of wastewater in a reservoir, comprising:
(a) a sheet of material, said sheet of material being flexible, impermeable, of predetermined size, and disposed in said reservoir such that:
(1) a first zone conducive to anaerobic digestion treatment is created below said sheet of material where:
(A) said wastewater is treated via anaerobic digestion,
(B) a once treated effluent is produced following anaerobic digestion, and
(C) bottom sludge is periodically removed,
(2) a second zone exposed to the sun and atmosphere and conducive to floating aquatic plant treatment is created above said sheet of material where:
(A) batches of said once treated effluent receives floating aquatic plant treatment by growing a multitude of at least one type of floating aquatic plant on the surface of said once treated effluent,
(B) batches of a twice treated effluent are produced following floating aquatic plant treatment,
(C) floating aquatic plant biomass from floating aquatic plant growth is periodically harvested and used for a second useful purpose, and
(D) bottom sludge is periodically removed,
(3) sufficient slack is provided in said sheet of material to compensate for changes in the liquid volume of at least one of said first zone and said second zone, and
(4) biogas evolving from anaerobic digestion in said first zone is diverted by said sheet of material to at least one area to be collected and used for a first useful purpose,
(b) a first means for conveying said wastewater to said first zone,
(c) a second means for conveying said once treated effluent from said first zone to said second zone,
(d) a third means for collecting said biogas diverted by said sheet of material, and
(e) a fourth means for discharging batches of said twice treated effluent from said second zone,
whereby said sheet of material is disposed in said reservoir such that said first zone conducive to anaerobic digestion treatment and said second zone conducive to floating aquatic plant treatment are created, sufficient slack is provided in said sheet of material to compensate for changes in the liquid volume of at least one of said first zone and said second zone, and biogas is diverted to at least one area to be collected and used for said first useful purpose.
2. The method of
(a) biodegradable agricultural animal wastewater,
(b) biodegradable wastewater,
(c) biodegradable municipal wastewater,
(d) biodegradable domestic wastewater, and
(e) biodegradable industrial wastewater.
3. The method of
(a) water hyacinths,
(b) duckweeds,
(c) pennywort, and
(d) water ferns.
4. The method of
(a) assimilating macronutrients, micronutrients, and metals into floating aquatic plant biomass,
(b) attached microbial growth on the roots of floating aquatic plants,
(c) adsorption of metals and suspended solids by floating aquatic plants, and
(d) entrapment of suspended solids in the root zone of the floating aquatic plants.
5. The method of
6. The method of
7. The method of
(a) use as a source of energy via combustion of said biogas,
(b) use as a source of heat via combustion of said biogas, and
(c) use as a source of electricity via combustion of said biogas.
8. The method of
9. The method of
(a) use as a source of biogas via anaerobic digestion of said floating aquatic plant biomass in said first zone,
(b) use as a source of biogas via anaerobic digestion of said floating aquatic plant biomass,
(c) use as an animal feed,
(d) use as compost,
(e) use as a green manure,
(f) use as a fertilizer, and
(g) use as an energy source via incineration of said floating aquatic plant biomass.
10. The method of
(a) adding chemicals to adjust the pH,
(b) adding chemicals to adjust the alkalinity,
(c) adding chemicals to control algal growth,
(d) adding chemicals to control disease-transmitting vectors,
(e) adding chemicals to control insects,
(f) adding water for the purpose of dilution,
(g) adding water to reduce the salinity,
(h) adding macronutrients, and
(i) adding micronutrients.
11. The method of
12. The method of
(a) volatilizing ammonium nitrogen,
(b) adding chemicals to adjust the pH,
(c) precipitating suspended solids via chemical precipitation, and
(d) precipitating phosphorus via chemical precipitation.
13. The method of
14. The method of
15. The method of
(a) a reuse means,
(b) a granular media filter,
(c) an animal confinement facility,
(d) spray fields,
(e) a wetland, and
(f) the environment.
17. The apparatus of
(a) an existing anaerobic lagoon,
(b) a lagoon,
(c) a pond,
(d) a tank, and
(e) a concrete cell.
18. The apparatus of
(a) high density polyethylene,
(b) medium density polyethylene,
(c) polyethylene,
(d) polyvinyl chloride,
(e) polypropylene,
(f) ethylene propylene diene M-class rubber, and
(g) rubber.
19. The apparatus of
20. The apparatus of
(a) use as a source of energy via combustion of said biogas,
(b) use as a source of heat via combustion of said biogas, and
(c) use as a source of electricity via combustion of said biogas.
21. The apparatus of
22. The apparatus of
(a) use as a source of biogas via anaerobic digestion of said floating aquatic plant biomass in said first zone,
(b) use as a source of biogas via anaerobic digestion of said floating aquatic plant biomass,
(c) use as an animal feed,
(d) use as compost,
(e) use as a green manure,
(f) use as a fertilizer, and
(g) use as an energy source via incineration of said floating aquatic plant biomass.
23. The apparatus of
25. The apparatus of
(a) an existing anaerobic lagoon,
(b) a lagoon,
(c) a pond,
(d) a tank, and
(e) a concrete cell.
26. The apparatus of
(a) high density polyethylene,
(b) medium density polyethylene,
(c) polyethylene,
(d) polyvinyl chloride,
(e) polypropylene,
(f) ethylene propylene diene M-class rubber, and
(g) rubber.
27. The apparatus of
(a) use as a source of energy via combustion of said biogas,
(b) use as a source of heat via combustion of said biogas, and
(c) use as a source of electricity via combustion of said biogas.
28. The apparatus of
(a) use as a source of biogas via anaerobic digestion of said floating aquatic plant biomass in said first zone,
(b) use as a source of biogas via anaerobic digestion of said floating aquatic plant biomass,
(c) use as an animal feed,
(d) use as compost,
(e) use as a green manure,
(f) use as a fertilizer, and
(g) use as an energy source via incineration of said floating aquatic plant biomass.
29. The apparatus of
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This application claims the benefit of provisional patent application No. 61/043,117 filed Apr. 7, 2008 by the present inventor.
Not Applicable
Not Applicable
1. Field
This application generally relates to an apparatus and method for wastewater treatment and more specifically to an apparatus and method incorporating natural systems for treatment and management of agricultural animal wastewater.
2. Prior Art
Agricultural animal waste disposal is a major problem. Over the past several decades, increased demand for meat and dairy products has facilitated the rapid growth of the commercial livestock industry. The increased demand and subsequent growth of the industry has led to the utilization of more centralized higher capacity farming operations. These farming operations are sometimes referred to as concentrated animal feeding operations (CAFO's). While these CAFO's may be more productive and cost efficient, they come with the down side of manure management issues. As the commercial livestock industries use of CAFO's has increased, so has environmental concerns over the impact their manure waste has on water and air quality.
Environmental concerns over manure waste from CAFO's are especially pronounced for CAFO's that produce liquid manure waste that is treated and managed using lagoon-spray field systems. Lagoon-spray field systems are systems that generally treat liquid manure waste in large anaerobic lagoons and then intermittently dispose of it through land applications. This system was developed in the early and mid twentieth century prior to the current trend in high concentrated livestock operations. As the livestock industry has expanded, treatment of liquid manure waste using lagoon-spray field systems has come under increased public and governmental scrutiny due to environmental concerns over leaks, spills, odors, and ammonia emissions from the anaerobic lagoons as well as the high nutrient content of the lagoon effluent that is applied to spray fields. Lagoon effluent often contains high levels of biochemical oxygen demand (BOD), Nitrogen (N), and Phosphorus (P) that cannot be decreased to acceptable levels by anaerobic treatment alone. In recent years, States and Federal agencies have promulgated strict rules and regulations governing lagoon-spray field systems in agricultural operations. In some cases, moratoriums on the use or permitting of new lagoon-spray field systems have been enacted.
The swine farming industry in North Carolina is a great example of a commercial livestock industry that has migrated to the use of CAFO's over the past several decades and still primarily uses lagoon-spray field systems to treat and manage liquid manure waste. In 1998 the State of North Carolina enacted a moratorium that prevented the construction and permitting of new lagoon-spray field systems until an environmentally superior waste management technology or process could be developed. In 2000 and 2002, the Attorney General of North Carolina entered into agreements with private companies to promote the identification and development of environmentally superior waste management technologies for use on North Carolina swine farms owned by the companies. This agreement is commonly referred to as the “Smithfield Agreement”. The Smithfield Agreement defines an environmentally superior technology (EST) as any technology, or combination of technologies that:
Although considerable time, money, and effort has been put towards developing an EST in North Carolina, an EST candidate has yet to be developed or identified that meets the definition of an EST, nor has a candidate reached permittable status. As a result, in 2007 with the passing of Senate Bill 1465, the State of North Carolina converted what had been a temporary 10 year moratorium on lagoon-spray field systems into a permanent moratorium. This has permanently curtailed the growth of the industry in North Carolina until a solution to the problem is found.
While the lagoon-spray field system problem and well defined requirements for a solution described here are specific to North Carolina, the problem and its solution are applicable far beyond the boarders of North Carolina. The situation in North Carolina is simply a microcosm of the broader manure management problem the commercial livestock industry is facing across the United States. In addition to the EST candidates evaluated under the Smithfield Agreement listed above, the following are additional prior art examples of efforts to improve agricultural animal waste treatment with similar disadvantages; U.S. Pat. No. 4,432,869 (Groeneweg et al.), U.S. Pat. No. 5,078,882 (Northrop), U.S. Pat. No. 5,135,659 (Wartanessian), U.S. Pat. No. 5,137,625 (Wolverton), U.S. Pat. No. 5,200,082 (Olsen et al.), U.S. Pat. No. 5,545,560 (Chang), U.S. Pat. No. 5,863,434 (Masse et al.), U.S. Pat. No. 5,885,461 (Tetrault et al.), U.S. Pat. No. 6,083,386 (Lloyd), U.S. Pat. No. 6,113,788 (Molof et al.), U.S. Pat. No. 6,139,743 (Park et al.), U.S. Pat. No. 6,190,566 (Kolber), U.S. Pat. No. 6,284,054 (Galvin), U.S. Pat. No. 7,001,512 (Newsome), U.S. Pat. No. 7,279,104 (Keeton, Jr.), U.S. Pat. No. 7,422,680 (Sheets, Sr.), U.S. Pat. No. 7,481,935 (Olivier)
One of the main problems with many of the prior art examples listed above and the industries approach to the problem in general is that the focus has tended to be on technologies and processes that are more appropriate for large scale waste treatment operations. e.g. solids separation, aeration, heating etc. While CAFO's are by name “concentrated”, the volume of wastewater they produce is rather decentralized as compared to advanced wastewater treatment facilities that take advantage of economies of scale. Waste treatment technologies that can meet the “technically feasible” requirements of an EST have existed for years but are too expensive and complicated to construct and operate at the farm level. They are expensive to build, are too complicated operate without significant oversight, and have high energy requirements. The key to solving the problem lies in finding an adequate treatment process that is also “economically and operationally feasible” for the farmer and commercial livestock industry. This thought is echoed by the following statement on the North Carolina State University College of Agriculture and Life Sciences' Smithfield Agreement website: “The swine industry is an important part of North Carolina's economy. The alternative waste management technologies being evaluated are designed not only to treat waste in a manner that protects the environment but also to treat waste in an economically feasible manner that allows the swine industry to survive” [6].
Another problem with many of the prior art examples listed above, and the industries approach to the problem in general is that they have tended to focus on year round treatment of waste. Treatment systems utilizing year round treatment and frequent or continuous discharge are more difficult to permit as the regulatory community less likely to permit a treatment system where there is little opportunity for management and oversight of the discharges. Year round treatment is especially problematic for treatment systems that employ predominantly natural systems for waste treatment (e.g. wetlands) due to the fact that the winter temperatures experienced for most of the United States have a negative effect on their operation. While all waste treatment methods rely on natural responses such as gravity for sedimentation or natural components such as biological organisms, a natural system for waste treatment depends primarily on its natural components to achieve the intended purpose. A natural system might typically include pumps and piping for waste conveyance but would not depend on external energy sources exclusively to maintain the major treatment responses [5]. As such, a natural system (or systems) for waste treatment has an advantage in that it would cost less to build, is easy to operate, and requires less energy. However, these natural systems have not proved to be an adequate solution to the problem because of reduced effectiveness during the colder winter months.
Specifically, many of the prior art examples listed above have one or more of the following problems:
While various systems have been developed for treating agricultural animal wastewater, including the EST candidates and prior art listed above, there still remains a need in the art for a technically, operationally, and economically feasible agricultural animal wastewater treatment system that costs less to build, is easier to understand and operate, and requires little energy input. A method based primarily on natural systems for agricultural animal wastewater treatment has the best chance for succeeding as these systems require less equipment with moving parts, have low operational energy requirements, and are simple for farmers to understand and use.
For the purpose of summarizing the invention and this specification, one embodiment of the apparatus and method is a technically, operationally, and economically feasible agricultural animal wastewater treatment system that costs less to build, is easier to understand and operate, and requires little energy input.
The method predominantly employs natural systems for wastewater treatment; an initial anaerobic digestion treatment in one zone followed by batch floating aquatic plant treatment in a second zone. Temporary storage capacity in one or both treatment zones allows for batch floating aquatic plant treatment in the second zone and subsequently batch discharges. The batch floating aquatic plant treatment of effluent following anaerobic digestion treatment and the subsequent batch discharge provides increased control of the treatment process. For example, the batch of anaerobic digestion treatment effluent can receive floating aquatic plant treatment until treatment goals are met which allow for discharge or reuse. In addition, for locations where climatic conditions are not ideal year round, this increased process control allows for batch floating aquatic plant treatment to only take place during the growing season of the floating aquatic plants utilized for treatment.
The apparatus reduces the land area and upfront construction cost required for the system by subdividing an existing or newly constructed anaerobic lagoon to create an anaerobic digestion treatment zone below a sheet of material and a floating aquatic plant treatment zone above the sheet of material. In addition to reducing the land area required for treatment, the sheet of material is disposed in the lagoon such that it facilitates the collection of biogas evolving from anaerobic digestion treatment beneath it by diverting biogas to areas to be collected.
Both of the natural systems for wastewater treatment employed by the method described here produce useful byproducts. Anaerobic digestion produces biogas and floating aquatic plant treatment produces floating aquatic plant biomass. The opportunistic collection and use of biogas and floating aquatic plant biomass result in additional benefits. In this embodiment, the floating aquatic plant biomass is placed into the anaerobic digestion treatment zone where it is digested to produce additional biogas. The additional biogas produced results in more cost effective biogas capture and shortens the payback period for the biogas infrastructure. Digesting the floating aquatic plant biomass on site in the anaerobic digestion treatment zone also eliminates transportation costs, one of the problems with utilizing floating aquatic plant biomass for a useful purpose.
Other advantages of one or more aspects of the apparatus and method are that it:
A first embodiment of the apparatus and method is illustrated by
In this first embodiment of the apparatus and method, untreated agricultural animal wastewater 21 is conveyed 15 to an anaerobic digestion treatment zone 10 below a sheet of material 8 where it receives anaerobic digestion treatment 22. Following sufficient anaerobic digestion treatment 22 and temporary storage, the once treated effluent is conveyed 16 to a floating aquatic plant treatment zone 11 above the sheet of material 8 where it undergoes conditioning 23 by diluting it with a retained portion of twice treated effluent from the previous batch. Following dilution, the batch once treated effluent receives floating aquatic plant treatment 24. In this embodiment the floating aquatic plants 14 utilized for treatment are water hyacinth (eichhornia crassipes). Following sufficient batch floating aquatic plant treatment 24, the batch of twice treated effluent is optionally polished 25 and then a portion is conveyed 17 to be discharged through a granular media filter to the environment 26A. The remaining portion is for diluting a subsequent batch of once treated effluent. Biogas evolving from anaerobic digestion treatment 22 below the sheet of material 8 is diverted by the sheet of material 8 to a biogas collection means where the biogas is collected and combusted to generate electricity 27A. Floating aquatic plant biomass generated from floating aquatic plant treatment 24 is harvested and transferred to be digested 28A in the anaerobic digestion treatment zone 10. This embodiments use of floating aquatic plant biomass is particularly synergistic as it eliminates the cost of transporting floating aquatic plant biomass and increases the return on the biogas collection means investment by increasing biogas production and generating more electricity.
Batch Floating Aquatic Plant Treatment of Anaerobically Treated Effluent Utilizing Water Hyacinth:
Anaerobic digestion treatment of agricultural animal wastewater is well understood. The following provides information and an example calculation demonstrating how batch floating aquatic plant treatment utilizing water hyacinth (Eichhornia crassipes), in conjunction with conventional anaerobic digestion treatment, can substantially treat a years worth of wastewater produced by a swine farm in a single growing season. For locations where the climate allows for year round water hyacinth growth/treatment, treatment goals would only be easier to achieve.
Water Hyacinth Characteristics:
Calculation:
The calculation below demonstrates how the N, P, and BOD contained in anaerobically treated swine farm effluent is substantially treated by batch floating aquatic plant treatment utilizing water hyacinth. While the detailed description of the first embodiment above and referenced figures do not provide dimensions, the liquid surface of the floating aquatic plant treatment zone 13 is assumed to be 50,000 square feet for the purpose of the calculations below.
Parameters for a swine nursery with 2,600 head of swine at 35 pounds/head average [4 and 8]:
Effluent parameters for anaerobic treatment of swine wastewater [2]:
One thousand pounds of water hyacinth placed on a 50,000 square foot wastewater surface at the beginning of a growing season would grow to more than 500,000 pounds in 9 weeks. This would equal a 10 pounds per square foot wet weight density. After harvesting to 25% coverage (125,000 pounds) the water hyacinth would grow back to 500,000 pounds in approximately 2 weeks (repeat as necessary). Based on this, 1 million pounds of water hyacinth could be grown in approximately 12 weeks (84 days). For reference, the growing season for water hyacinth would be approximately 120-150 days in North Carolina.
Summary:
Based on the above information and example calculation, it is feasible for batch floating aquatic plant treatment utilizing water hyacinth (eichhornia crassipes), in conjunction with conventional anaerobic digestion treatment, to substantially treat a years worth of wastewater produced by the example swine nursery in a single growing season.
Advantages:
Thus, the reader will see that the first embodiment of the method and apparatus provides a technically, operationally, and economically feasible agricultural animal wastewater treatment system that costs less to build, is easier to understand and operate, and requires little energy input. In addition to eliminating the discharge of animal waste to surface waters and groundwater, this embodiment also:
A second embodiment of the apparatus and method is illustrated by
In this second embodiment of the apparatus and method, untreated agricultural animal wastewater 21 is conveyed 15 to an anaerobic digestion treatment zone 10 below a sheet of material 8 where it receives anaerobic digestion treatment 22. Following sufficient anaerobic digestion treatment 22 and temporary storage, the once treated effluent is conveyed 16 to a floating aquatic plant treatment zone 11 above the sheet of material 8 where it is optionally conditioned 23 prior to receiving batch floating aquatic plant treatment 24. In this embodiment the floating aquatic plants 14 utilized for treatment are water hyacinth (eichhornia crassipes). Following sufficient batch floating aquatic plant treatment 24, the batch of twice treated effluent is optionally polished 25 and then conveyed 17 to be discharged 26. Biogas evolving from anaerobic digestion treatment 22 below the sheet of material 8 is diverted by the sheet of material 8 to a biogas collection means where the biogas is collected to be used for a first useful purpose 27. Floating aquatic plant biomass generated from floating aquatic plant treatment 24 is harvested from the floating aquatic plant treatment zone 11 to be used for a second useful purpose 28.
A third embodiment of the apparatus and method is illustrated by
In this third embodiment of the apparatus and method, untreated agricultural animal wastewater 21 is conveyed 15 to an anaerobic digestion treatment zone 10 below a sheet of material 8 where it receives anaerobic digestion treatment 22. Following sufficient anaerobic digestion treatment 22 and temporary storage, the once treated effluent is conveyed 16 to a floating aquatic plant treatment zone 11 above the sheet of material 8 where it is optionally conditioned 23 prior to receiving batch floating aquatic plant treatment 24. In this embodiment the floating aquatic plants 14 utilized for treatment are water hyacinth (eichhornia crassipes). Following sufficient batch floating aquatic plant treatment 24, the batch of twice treated effluent is optionally polished 25 and then conveyed 17 to be discharged 26.
A fourth embodiment of the apparatus and method is illustrated by
In this fourth embodiment of the apparatus and method, untreated agricultural animal wastewater 21 is conveyed 15 to an anaerobic digestion treatment zone 10 below a sheet of material 8 where it receives anaerobic digestion treatment 22. Following sufficient anaerobic digestion treatment 22 and temporary storage, the once treated effluent is conveyed 16 to a floating aquatic plant treatment zone 11 above the sheet of material 8 where it receives batch floating aquatic plant treatment 24. In this embodiment the floating aquatic plants 14 utilized for treatment are water hyacinth (Eichhornia crassipes). Following sufficient batch floating aquatic plant treatment 24, the batch of twice treated effluent is then conveyed 17 to be discharged 26.
Additional embodiments are illustrated as flow charts in
In the
In the
In the
In the
There are various possibilities for how the method could be implemented independent of the apparatus. The alternative embodiment illustrated in
Another alternative embodiment (no Fig.) would be the two lagoon set up illustrated in
Accordingly, the reader will see that one or more embodiments of the method and apparatus provide a technically, operationally, and economically feasible agricultural animal wastewater treatment system that costs less to build, is easier to understand and operate, and requires little energy input. In addition one ore more embodiments
While the above descriptions contain many specificities, these should not be construed as limitations on the scope of any embodiment, but as exemplifications of the presently preferred embodiments thereof. Many other ramifications and variations are possible within the teachings of the various embodiments. For example, various other types (species) or combinations of floating aquatic plant types can be utilized for floating aquatic plant treatment; the size, shape, or composition of the sheet of material can vary; the liquid conveyance means' can have many different forms; the biogas conveyance and collection means can have many different forms; the type, size, volume, liquid surface area, and number of reservoirs making up the two treatment zones could vary, etc. Thus, the scope of the invention should be determined by the appended claims and their legal equivalents, and not by the examples given.
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